US 8012203 B2
An intraocular lens for insertion into a capsular bag in order to focus incoming light toward a retina and process for manufacturing thereof along with concomitant reduced glare and improved vision provides for a center lens portion of a lens for focusing incoming light toward the retina and the surrounding lens portion for mounting the lens within the capsular bag. A surface roughness disposed on the surrounding lens portion is provided for reducing the glare due to non-focused light directed toward the retina from the intraocular lens with the roughness having a roughness level of between about Ra 45 and about Ra 350.
1. An intraocular lens, comprising:
a center lens portion for focusing incoming light toward the retina of an eye;
a surrounding lens portion having an anterior surface, a posterior surface, and a peripheral edge surface, said peripheral edge surface intersecting at least one of said anterior and posterior surfaces;
a glare-reducing rough surface disposed on the surrounding lens portion, the rough surface having a surface roughness level of about Ra 180 μin, the rough surface having a Gaussian distribution width sigma of at least 1 when illuminated by an incident light beam, and scattering data from the illuminated rough surface is fitted to a Gaussian distribution model, the incident light beam having a wavelength of 633 nanometers and illuminating the surface at a 55 degree incident light angle; and
at least one haptic coupled to the surrounding lens portion;
wherein the rough surface is disposed on the peripheral edge surface, and the center lens portion having no surface roughening applied thereto.
2. The lens according to
3. The lens according to
4. The process according to
The application is a continuation application of, and claims priority to, application Ser. No. 12/163,912, filed Jun. 27, 2008, now U.S. Pat. No. 7,811,319, which is a divisional of, and claims priority to, application Ser. No. 10/638,036, filed Aug. 8, 2003, now abandoned, both of which are herein incorporated by reference in their entirety.
The present invention generally relates to apparatus and methods for improving vision of an eye with a cataractic lens. More particularly, the present invention relates to an intraocular lens for insertion into a capsular bag in order to focus incoming light toward a retina and still more particularly relates to a process of fabricating an intraocular lens, which includes roughening portions of the lens in order to reduce glare due to non-focused light directed toward the retina from the intraocular lens.
A typical intraocular lens (IOL) is formed from a suitable synthetic material, such as silicone, and shaped for insertion into an eye. The IOL may be utilized in place of, or, in addition to, the natural lens of the eye to correct vision. Often the IOL replaces the natural lens in the capsular bag after removal of the natural lens.
A number of different types of IOL's have been developed for correcting various types of vision disorders.
While most IOL's are suitable for correcting visual disorders, they also typically cause the recipient to experience undesirable side effects commonly referred to as “glare”.
This glare has been described as an arc, or pattern, with concentrated intensity and high local contrast. That is, the glare is a brightened pattern which is easily distinguished by the recipient over other images projected onto a retina by the lens. Accordingly, to reduce this glare perception, both the glare pattern intensity and the local contrast must be reduced below vision recognizable or perception thresholds.
Often, these glare effects which may be perceived as haloes, arcs of light, flashing of light, as well as shadows are often caused by peripheral edges of the implanted IOL.
Specifically designed IOL edges have proved to be very effective on reducing edge glare phenomenon. Rounded edges have proved to be able to reduce glare perception by breaking the glare light concentration of a specific pattern and thereby decreasing the glare pattern average intensity and local contrast.
Of particular importance in that regard is disclosed in U.S. Pat. No. 6,468,306 to Paul, Brady, and Deacon. This patent is incorporated in its entirety into the present application by this specific reference thereto. This design hereinafter may be referred to as OptiEDGE (Advanced Medical Optics, Santa Ana, Calif.) has been successfully designed to reduce edge glare. For instance, a rounded transition surface on the anterior side of the peripheral edge diffuses the intensity of reflected light, or a particular arrangement of straight edge surfaces refracts the light so as not to reflect, or does not reflect at all.
It has also been found and reported in U.S. Pat. No. 6,162,249 that the use of frosting, or roughening areas of the IOL can reduce glare. In this regard, the basic concept is the use of a roughened surface to avoid internally reflecting rays from causing the unwanted visual glare.
The present invention is directed to a process for fabricating a surface on an intraocular lens to provide optimum roughening thereof to produce a random scattering surface finish. In that regard, the present invention also encompasses an intraocular lens utilizing that the surface, a method for reducing glare from an intraocular lens onto a retina and ultimately a method for improving vision of an eye.
An intraocular, lens in accordance with the present invention for insertion into a capsular bag, is provided for focusing incoming light toward a retina. The lens generally includes a center lens portion for focusing incoming light toward the retina and a surrounding lens portion for mounting the lens within the capsular bag.
A surface roughness disposed on the surrounding lens portion is provided for reducing glare due to non-focused light directed toward the retina from the intraocular lens. The surface roughness has roughness level of between about Ra 45 and about Ra 350.
In accordance with an embodiment of the present invention, the surface roughness is produced by Electrical Discharge Machining and the surrounding lens portion comprises silicone.
More particularly, it has been found that a roughness level of about Ra 180 is particularly suitable for reducing glare. The surface roughness may be disposed on anterior and posterior surfaces of the surrounding lens portion and selected portions having the provided surface roughness may include at least one haptic for fixing a lens within the capsular bag.
Preferably, the surrounding lens portion includes a peripheral edge surface intersecting at least one of the anterior and a posterior surface to form a corner therebetween and a surface roughness, or frosting, is disposed on the anterior and posterior surfaces other than the corner.
Also in accordance with the present invention, a process for fabricating a surface on an intraocular lens is provided with the process comprising roughening a smooth lens surface by Electrical Discharge Machining to a roughness level of between about Ra 45 and about Ra 350.
In addition, the present invention provides for a process of fabricating an intraocular lens which includes providing a blank lens having a center lens portion and a surrounding lens portion and roughening the surrounding lens portion by electrical discharge machining to a roughness level of between about Ra 45 and about Ra 350.
Ultimately, the present invention provides a method for improving vision of an eye with a cataractic lens with the method including the steps of removing a cataractic lens from the lens capsule and inserting an intraocular lens into the capsule with the intraocular lens including a center lens portion for focusing incoming light toward the retina, a surrounding lens portion for mounting the lens within the capsular bag and a surface roughness disposed on the surrounding lens portion for reducing glare due to non-focused light directed toward the retina from the intraocular lens. The surface roughness has a roughness level of between about Ra 45 and about Ra 350.
Likewise, the present invention comprises using the method taught for phakic lenses and contemplates all of the disclosed steps with removal of the lens or during a “clear lens-ectomy” or procedure without removal of a cataractous or “cloudy” lens.
The advantages and features of the present invention will be better understood by the following description when considered in conjunction with the accompanying drawings in which:
With reference to
As more clearly shown in
The surface roughness has a roughness level of between about Ra 45 and about Ra 350 and preferably about Ra 180. Surface roughness is the arithmetic mean roughness value which is calculated from the integral of the absolute value of peak or valley with respect to a centerline, according to standard methods.
With reference to
The present invention provides for a roughened surface 24 on the lens-surrounding portion 14 as shown in
A discussion of random scattering is useful in understanding the present invention. A random scattering surface can be modeled at the surface with uniform scattering in all directions in an ideal case such as a Lambertian Scattering Surface shown in
The distribution amplitude represents a scattering level at a specific scattering direction. It is the ratio of all energy associated to the scattered rays to the total energy associated to all reflected or transmitted rays. The larger the scattering level the more energy associated with the scattering ray.
The intraocular lens 10 and the surface roughness, or frosting, 24 provided thereon is fabricated by providing a blank lens, preferably silicone, having the center lens portion 12 and surrounding lens portion 14 and thereafter roughening the surrounding lens portion 14 by Electrical Discharge Machining utilizing apparatus 60 diagramed in
Generally, the Electronic Discharge Machining apparatus 60 includes an electrode tool 62, a slide table 64, and a work piece 66 for supporting the intraocular lens 10 (not shown in
In a simplistic description of one mode of operation, the lens 10, 10 a is disposed on the work piece and the pulsed generator and slide table manipulated to provide the roughness 24 on the lens 10, 10 a to a specified surface roughness Ra. As a specific example a program usable on an Electrical Discharge Machine available at Porex Medical Products in Ontario, Calif. is set forth in Table 1 for providing a Ra 180 surface on silicone lenses 10, 10 a as indicated by the surface 24 shown in
Six IOL's having an edge roughness 26 from Ra 45 to Ra 490 were subjected to scattering measurements at 35° and 55° incident light angles with the light of 514 nm and 633 nm, respectively.
From the measured scattering results, it has been found that all surface scattering follow a Gaussian distribution by fitting the measured data to a Gaussian scattering model, as shown in
Measured scattering level is about 0.993, as shown, and, as shown in
In view of variation of distribution width sigma shown in
The corresponding glare pattern average intensity and local contrast of the lenses is shown in Table 2
It should be apparent that the results for the frosted lenses as shown in
Although there has been hereinabove described a specific glare reducing rough surfaces in accordance with the present invention for the purpose of illustrating the manner in which the invention may be used to advantage, it should be appreciated that the invention is not limited thereto. That is, the present invention may suitably comprise, consist of or consist essentially of the recited elements. Further, the invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art, should be considered to be within the scope of the present invention as defined in the appended claims.